US2746352A

US2746352A - Optical indicating device

Info

Publication number: US2746352A
Application number: US266672A
Authority: US
Inventors: Roger S Estey
Original assignee: Individual
Current assignee: Individual
Priority date: 1952-01-16
Filing date: 1952-01-16
Publication date: 1956-05-22
Anticipated expiration: 1973-05-22

Description

nection with the accompanying drawings.

2,746,352 omcALj mmcn'rme nnvrcn Roger SrEstey, China Lake, Calif.

Application mus -'16,, 19 52, serial No. 266,672

' 4- Claims. ct. sit-=14 This inventionr'elates to optical indicating devices and has particular reference to a new and improved form of such device which utilizes the optical lever principle and with which the use or collimators, projectors and telescopes is not usually necessary and which, therefore, provides a relatively simple, compact and inexpensive device, for measuring small-changes in angle.

An object of the invention is tp provide a relatively simple, compact and inexpensive optical indicating device.

Another object is to provide a device of the type set forth which utilizes the optical lever principle.

Another object of the'invention is to provide a device of the type set forth with which itls possible to obtain a multiplication of the reading.

Another ob ector the invention is to provide a simple,

ni-t d States ates rugged and relatively inexpensive or economical micrometric indicator {or use in making fine measurements in machine shops and the like. t

Other objects and advantages of the invention will be apparent ,from the following description taken in"c0It It will be understood that changes maybe made in the details of construction and arrangement of parts in the device shown embodying the invention without departing from the scope of the invention-as set forth in the accompanying-claims.

Referring to the drawings: Y

Fig. 1 is a diagrammatic view illustratingthe principle I utilized in the invention;

Fig. 2 is a side elevation, partly in section, of one form of a micrometric indicator embodying the invention;

'Fig. 3 is a diagrammatic view illustrating the operation of the device;

Fig. 4 is a diagrammatic elevational view of another form of theinvcntion;

Fig. 4a is a fragmc tary plan vicwof a portion of the arrangement shown in i ig. 4; and

Fig. 5 is a further view of thearrangcment of Fig. 4 but taken in the plane perpendicular to that of Fig. 4.

As previously stated, the present invention relates to. optical indicating devices utilizing the optical lever principle. This principle, which'is well known in the art, utilizes the property of a rotatable plane mirror to turn a reflected ray of light through twice the angle of the mirror rotation. This principle is illustrated in Fig. 1 wherein the line 1-2 represents a'ray of light incident on the mirror M. The normal'to the mirror is shown at 2-N and the reflected ray is 2-4. in accordance with the well known law of reflection, angle, 1-2-N is equal to angle N--23. Now as the mirror M is rotated to the position indicated by M, pa shown in dotted lines in Fig. l,

'the reflected ray is 24-4 and the increase in deflection 2,746,352 Patented May 22, 1956 plexity ranging from simple projectors used with translucent scales to telescope and scale combinations and autocollimators. 1

In the present invention, I utilize a simple auxiliary op tical element, namely a fixed mirror or reflector whereby the eye of the observer, cooperating with the geometry of the device embodying the invention serves to identify the lines 20f sight without additional apparatus and this permits angular and linear quantities to be measured with high precision and hitherto unknown simplicity. Specifically, whatever the eye position may be, the re flection of the ray in the fixed mirror is observed and compared with the reflection of the corresponding ray in the rotatable mirror. reflcctionot' the first mentioned my in the fixed mirror is unchanged and serves to establish a new comparison with the new value of deviation of that ray reflected in the deviated position of the-movable mirror.

While the present invention may be employed in a large number of devices, it has been shown for the purpose of illustration, embodied in a micrometric indicator of the type commonly known as a lathe indicator, adapted for indicator comprises a base 10 carrying the plunger 11, the

movable mirror 12, the fixed mirror 13 and the scale 14. The plunger 11 is mounted for sliding movement without friction and without side play in a nicely fitted hole 10a in base 10. A leaf spring 15 has one end 15:: connected to the adjacent end 11a of plunger ll and a second leaf spring 16 which is parallel to leaf spring 15 is'secured at 16a to a shoulder on base 10 and the outer or free ends of the two leaf springs 15 and 16 are joined or connected to each other by means of the block 17 which has a portion extending between said springs and said block 17 carries or supports mirror or reflector 12. 7

On base 10 in adjacent relation with the normalposition of reflector or mirror llis provided a fixed reflector or mirror 13.

It will be seen that any movement of plunger 11 in its bore 10a will effect angular movement of leaf springs 15 and 16 and mirror or reflector ll'relative to stationary mirror or reflector 13.

The differential action of the two springs 15 and 16 translates a lateral movement originating in one end of one spring into a rotation (and translation) of the mirror 12 in the following manner as shown in Fig. 3 on an enof the springs is shown in full lines and indicated by the numbers 15 and 16 and the deflected position of the springs is shown in broken lines and indicated by 15' and 16' and the block 17 is shown in such adjusted position in broken lines and indicated by 17'. I

If, as shown in Fig. 3, the spacing between the springs is denoted by t, and the movement of plunger 11 by d and if it is assumed that the spring deflections are circular, then it is evident from the diagram that 0=d/t, where 9 denotes the angular deflection of the nirror 12 and the block 17. It is advantageous to use a small value of r in order to create a large angular movement of mirror 12, responsive to the linear movement of plunger 11.

The scale 14 which has been shown in both side and top views in Fig. 2, with the side view'being in its normal position and the top view being shown merely to facili rays by means ot-colllptators of varying degrees of v tate the explanation of the device, is-rigidly located to base i 10 by any suitable or convenient means. It is pointed out that it is advantageous to utilise a lar e distance or separation between scale 14 and mirrors or reflectors l2 and 13 in order to create a large linear nta'gnitication of the When the latter-mirror is rotated the pinion would serve aswell.

rays is identified a; the

the angular movement of .or marks on a transparent background or the reverse thereof.

It is essential, that scale l i be so disposed that the observer's eye 18, located tit some'point such as is indicated in Fig. 2, will setrt'mrtirgns.of the scale 14 and fiducial mark reflected in each ofthe mirrors 12 and 13. The two portions are indicated bythe numbersfl and 20. Each scale portion maybe complete like 19 or preferably one scale portion may comprisea simpletiducial mark, as 20. With the eye l8in any appropriate ppsition, and with the mirror 12 many position 'within its t'ange, the eye of the observer will see avirtual image of the fiducial mark 20 reflected inthezmirror'm and a virtual image of a series of scale marks-reflected in mirror 12. These images will be contiguousg and the virtual imagepf the fiducial mark will serve to identify a reading of the virtual image of the scale exactly as though a-real fiducial mark were contiguons' with-and slideably or adjustably related to a real scalefllust-so long as the eye 18 retains the appropriate parts of 'thejscale image in view, the readings will be correct because the-use of two adjoining and angular mir- T rors l2 and 13 ensures that the fiducial mark 20 of the scale element 19 will be viewed under comparable conditions not influenced. by the exact position of the eye 18. As is common to all precise'observations of juxtaposed .fiducial marks'and scales, precautioits'must be takento .avoid parallax.

In my invention parallax can be avoided as follows. A refe'renceplane is first established in the line of sight between the mirrors 12 and 13 and the eye 18. Such a ,plane is represented by the. line A- -A of Fig. 2. The

contour of the scale "is so adjusted that corresponding to any position of mirror 12 the distance along the indicated raypath from the scale 14 to the mirror 12 and 4 thence to the reference plane'AA shall be equal to the reference distance fromathefiducial mark 20 to the mirror l3 and thence'to the reference plane A-A. It is nppreciated that'this correction for pafallax is not precise,

depending to'some extent ,on the position of the eye 18. Nevertheless, within practical accuracy, it is a worthwhile correction in some cases.

As a micrometricindicator my invention is most useful in detecting small departures from a standard mcasu't'ement and is most accurate over a short range of scale divisions. It' d. t. and have the meanings previously assigned, and if R'isth e distance from the mirrors to the scale, then the magnification of thei-deviee is calculated as follows. Mirror system ror angle, namely 20,

In a practical embodiment of my invention it is en-- tirely feasible to let R=e2.0 and :=t).03 inch, indicating that a magnification of 1-50)( is readily obtainable.

It is not intended to limit my invention to the above example in which linear motion is translated to a magnified angular motion by differential springs. Any suitable niechanical movement such asa lever-system or rack and In Figs. 4, 4a and there is illustrated diagrammatically -'a somewhat more complicated, but superior form of my as the measuring" pencil. The reference pencil is controlled in the manner previously described. The meas uring pencil, however, is controlled by a plurality of reflections in the movable or adjustable mirror.

In Fig. 4 there is shown the disposition of the mirror and the light paths representative of this example by means of an elevation in cross section, the cutting plane being that containing the rays and the normals to the mirrors while Fig. 5 is in elevation in a plane perpendicularto Fig. 4. The means for rotating the measuring mirror are not shown because such means have been adequately described above in connection with the form of the device shown in Fig. 2.

With reference to Fig. 4 the eye 30 sees the virtual image of the fiducial mark 31 reflected in the reference mirror 32. The reference'pencil is boundedby the short dash line 33 and the full line 34 and its extension 34a. The virtual image is'further indicated in Fig. 4a which represents the significant portion of the field of view as seen from the eye point 30,

The eye 30 sees the virtual image of the scale 35 by successive reflections in the measuring mirror 36, the

under side 32 (which is also a mirror) and the measuring In the view shown in mirror 36 (used a second time). Fig. 4 the traces of the two mirrors in the plane of the diagram are parallel. In this particular example used to illustrate the invention, the mirror 32 must be thin and have sharp edges to permit the close juxtaposition of the virtual image of the fiducial mark 31 and the scale 35. The measuring pencil of rays is bounded by the full line 34, its

extensions

34b, 34c and 34d and the long dash line 37 with its extensions'37a, 37b and-37c.

In order to avoid parallax the distance from the reference surface 38-48 to the scale 35 via multiple reflections at the

mirrors

32 and 36 is made equal to the distance from the reference shrface38-38 to the fiducial mark 31 via the mirror 32.

In Fig. 5, the measuring mirror is shown tilted clockmirror 36 rotates. with the-respect to the remainder of the optical system and in so doing the ray multiply reflected in the rotated and fixed mirrors turns through four times the angle of the mirror rotation.

By a slight change in the technique of using this multi mirror optical indicator it is possible to obtain an angular scale reading which is not two or four but six times the angular rotation of the rotatable mirror. This additional magnification is obtained by interchanging the roles of

mirrors

32 and 36. In this form of my invention I choose to fasten mirror 36 rigidly with respect to the frame of the device, the fiducial mark 31 and the scale 35. The two-faced mirror 32 is arranged to rotate and to permit its rotation to be measured. The magnification of six is obtained by the combination of the double deflection of the image of mark 31 and the quadruple deflection of the 7 image of scale 35. I

In the cases illustrated in Figs. 4, 4a,and 5, and described above it may be advantageous to supplement the unaided eye with an appropriate type of telescopic auxiliary optical system.

The use and operation of the device embodying the foregoing descripvention. I

mirror and a fiducial mark optically aligned therewith.

i I claim:

1. An; optical indicating device including a first opaque a second opaque mirror and a scale optically aligned 8,746,852 6 therewith, said mirrors being in spbstantially the same 4. An optical indicating device including a stationary plane and adapted to reflect images in the same general first mirror, a tiltable second mirror,-said mirrors being direction, said first mirror and fiducial mark and said substantially in the same plane and adapted to reflect second mirror and scale being in adjacent relation images in the same general direction toward a common whereby from a common eye point the fiducial mark 6 eye point, an elongated scale visible in said mirrors from image is visible in said first mirror and the scale image said common eye point, comprising two parallel portions is visible in said second mirror and the images of said lying along its length, said scale being so located with scale and fiducial mark are contigupus, one of said mirrespect to said first and second mirrors that one parallel rors being adjustable relative to the other of said mirrors portion including a fiducial mark is reflected in the first to produce relative displacement of the images of said 10 mirror to said eye point, and the other parallel scale scale and fiducial mark. a support having a bore. a portion is reflected in said second mirror to said eye plunger in said bore a pair of springs supporting said point, a support having a bore, a plunger slidable in movable mirror, said springs being supported by said said bore, means actuated by said plunger to tilt said plunger and support respectively. second mirror in proportion to the amount of movement 2. An optical indicating device including a first opaque of the' plunger in a direction to apparently move the mirror and a fiducial mark optically aligned therewith, reflected image of said other scale portion longitudinally a second opaque mirror and a scale optically aligned with respect'to said portion including'the fiducial mark therewith, said mirrors being in substantially the same whereby the movement of said plunger in said bore may plane and adapted to reflect images 'in the same general be measured. direction, said first mirror and fiducial mark and said 5. An optical indicating device includinga stationary second mirror and scale being in adjacent relation first mirror and a tiltable second mirror, said mirrors whereby from a common eye point the fiducial mark being in substantially the same plane and adapted to image is visible in said first mirror'and the scale image reflect images in the same general direction toa common is visible in said second mirror and the images of said eye point, an elongated scale visible in both said mirrors scale and fiducial mark are contiguous, one of said mirfrom said common eye point, a support having a bore,' rors being displaceable relative to the other of said'mira plunger axially slid-able in said bore, means actuated I rors to produce relative displacemept of the images of by said plunger to tilt said second mirror in proportion said,scale and fiducial mark, a support having a bore, to the movement of the'plunger and in a direction to a plunger in said bore, a pair of parallel springs support- 80 apparently move the reflected image of said scale in said ing said movable mirror, said parallel springs being supsecond mirror with respect to said scale reflected in said ported by said plunger and support respectively. first mirror whereby the movement ofsntd plunge: in .t 3. In an optical indicating devlc including a fitted said here may be measured. mirror and a, movable mirror, a seal: visible in each at a I said mirrors froin a common eye point. a aapport fiml u v References Cltottlnthe tile of this patent said movable m rror compra ng tw norms y para o flexible support elements rigidly sccigred at one end to UNITED STATES PATENTS element slidable in the direction of'parallelism of said flexible elements, whereby movement of the plunger will p produce relative apparent displacement of said scale as I, a 1' I seen in said movable mirror with respect to said scale 629,171 France .e-,.. Dec. 8.11930 seeninnidflxedmirrorbytiltingsqfidmovablemirrqr. ,t a I FOREIGN MTBNTS' said movable mirror. one of said he lble elements being 05 1 l" 1 secured at its other end to a stati iinary base and the figrgnu nnun Ffiaylg, a I a Y I